Abstract

Prioritisation of areas for biodiversity conservation has been debated largely in the terrestrial realm. In response to the increasing need for conservation efforts in the marine environment, this study compiles and analyses available data on species distributions and compares different approaches to the selection of marine reserve sites for the conservation of South Africa's coastal fish diversity. Species richness decreases from Mozambique southwards to the Cape, due mainly to a subtropical subtraction effect, and is uniformly low along the west coast. The number of species endemic to southern Africa is also higher in the east than west, and peaks in the region of Port Elizabeth. Hotspot analysis does not provide a useful site-selection tool in a linear (coastal) analysis, at least in the absence of abundance data. Cluster analysis shows that coastal fish conform to the same three biogeographical provinces as other marine taxa, although the zonal boundaries vary between groups and are particularly difficult to pinpont for fish. Multidimensional scaling better illustrates the fairly even rate of species turnover east of Cape Point. The selection of sites at the centre and boundaries of vaguely defined biogeographical zones is thus relatively difficult, and excludes several localised endemics. These problems can be resolved by using complementarity analysis. In the absence of abundance data, to avoid 'reserving' species at the periphery of their ranges, a pragmatic approach is developed, in which data are refined to include species' core distributions only. The roles of existing marine reserves are also considered in assessing future conservation needs.